A touch panel is a user interface (UI) capable of simply and instinctively inputting, and receiving, a user manipulation by touching a surface or a defined contact surface of a display with a finger or an electronic pen. Such a touch panel has been applied to various applications such as a navigation terminal, a telematics terminal, a personal digital assistant (PDA), a laptop computer, a notebook computer and a smart phone.
The touch panel uses touch recognition technologies such as a resistive overlay, a capacitive overlay, a surface acoustic wave and an infrared beam. Since the touch panel provides an instinctive and flexible UI and has high function extensibility, it has been utilized as a control system of a vehicle which becomes complex due to an increase of convenience, safety and infotainment functions, but has a limit in that it does not provide a blind control because the touch panel recognizes a touch position at the instant at which a user's finger touches the touch panel.
In order to solve the above-mentioned problem, a force based touch pad that classifies search and input intentions of the user by sensing force touch has been suggested. In such a force-based touch pad, the touch pad may be bent or distorted by a force touch of the user. As a result, a force magnitude and a touch position of the force touch may be inaccurately measured. Accordingly, the related art addresses that error by suggesting that a torsion of the touch pad is corrected by calibration.
However, since the force based touch pad according to the related art allows the touch pad to be bent, it has a structure in which it is difficult to detect a magnitude of an absorbed force due to a modification of the pad. As a result, when the search and input intentions of the user are classified by the magnitude of force, an accuracy of recognition may be degraded.